Russula fusiformata Y.Song, 2022

Song, Yu, 2022, Species of Russula subgenus Heterophyllidiae (Russulaceae, Basidiomycota) from Dinghushan Biosphere Reserve, European Journal of Taxonomy 826, pp. 1-32 : 7-11

Russula fusiformata Y.Song sp. nov.

MycoBank: MB828231

Index Fungorum: IF559326

Figs 2–3 , 6b

Diagnosis

Russula fusiformata sp. nov. is distinguished by its ITS sequence with a similarity less than 95% compared to other known species. In morphology, it is mainly characterized by the lavender blush to rosy brown pileus with crenate margin, adnate lamellae, metachromatic pileipellis with slender furcated and septate terminal elements, and fusiform cheilocystidia with sharp apices.

Etymology

The name refers to the fusiform cheilocystidia with sharp apices.

Material examined

Holotype CHINA • Guangdong Province, Zhaoqing City, Dinghushan Biosphere Reserve, on the ground in evergreen broad-leaf forest mainly with Fagaceae trees; 27 May 2015; Y. Song, K15052703 ; GenBank no.: MK049978 ( ITS); GDGM75333 .

Additional material

CHINA • Guangdong Province, Zhaoqing City, Dinghushan Biosphere Reserve, on the ground in evergreen broad-leaf forest mainly with Fagaceae trees; 12 Jun. 2015; Y. Song; GenBank no.: MK049979 ( ITS); GDGM75332 .

Description

Basidiomata medium-sized. Pileus 6–9 cm in diam., applanate to plano-concave with a depressed center, lavender blush (#FFF0F5) with thistle tint (#D8BFD8), often tan (#D2B48C) to rosy brown (#BC8F8F) at center, rarely with a pale yellow tinge; margin entire or waved, striate. Lamellae adnate, ivory (#FFFFF0), cream yellow when dried, unchanging after bruising, equal, not or rarely forking, with even, concolorous edges. Stipe 6–8 × 1.5–2 cm, white (#FFFFFF), cylindrical, smooth, dry, central, solid, often longitudinally rugulose. Context 6–8 mm thick, whitish, unchanging after bruising or with FeSO 4, cream when dry. Taste mild. Odor indistinct. Spore print whitish.

Basidiospores subglobose to broadly ellipsoid, (40/2/2) (4.8–)5.6–6.5–7.4(–7.6) × (4.5–)5.1–5.7–6.3(– 6.7) μm, Q = (1–)1.04–1.15–1.28(–1.3), hyaline in 5% KOH; ornamentation amyloid, composed of conical to subcylindrical warts, not exceeding 0.7 μm in height, mostly isolated, but a few connected with short lines, but not forming a reticulum; suprahilar spot distinct, not amyloid. Basidia 26.5–42–49.5 × 8–12– 14 μm, 4-spored, rarely 2-spored, narrowly cylindrical to subcylindrical or broadly clavate; sterigmata not exceeding 5.7 μm in length. Lamellar trama mainly composed of nested spherocytes (13–55 × 7.5– 42 μm) surrounded by connective hyphae. Pleurocystidia 43–50–53 × 7–8–9 μm, slender, cylindrical to subfusiform, apex obtuse, bluntly acuminate or mucronate, with abundant granular contents; negative in SV. Cheilocystidia 36.5–52–78 × 5–9–11 μm, clavate to fusoid, often with bluntly acuminate to mucronate apices, thin-walled, with refractive contents, unchanged in SV. Marginal cells not differentiated. Pileipellis metachromatic in cresyl blue, 67–140.5 μm thick, composed of suprapellis and subpellis; suprapellis a trichoderm composed of ascending to erect hyphae and subpellis composed of horizontally oriented hyphae 1.8–5 μm in diam.; terminal elements at center 5.5–14 × 3–8 μm, cylindrical, apices obtuse; terminal cells at margin slender cylindrical with obtuse apices. Pileocystidia 15.5–64 × 2–10 μm, always one-celled, slender, apex mucronate or subterminally constricted, cylindrical to clavate. Stipitipellis a cutis, composed of thin-walled, often ramifying, septate hyphae 1.5–3.6 μm in diam. Caulocystidia 19–31 × 3–10.5 μm, subcylindrical to fusoid, bluntly acuminate or mucronate, with refractive contents. Clamp connections absent.

Remarks

Our phylogenetic analysis based on ITS shows that Russula fusiformata sp. nov. is well nested in subsect. Cyanoxanthinae Singer and relatively close to R. dinghuensis J.B.Zhang & L.H.Qiu and R. subpallidirosea J.B.Zhang & L.H.Qiu. The three species have a common habitat and distribution, namely all are gregarious in monsoon evergreen broad-leaf forest and mixed pine-broad-leaf forest in DHSBR. Russula dinghuensis (Appendix 1) is characterized by the olive green pileus with acute and incurved margin, white and rarely forked lamellae, thick metachromatic pileipellis. Russula subpallidirosea (Appendix 3) can be recognized by the pale pink to pale grayish-pink pileus, white and forked lamellae, metachromatic pileipellis with short terminal elements. Russula fusiformata can be differentiated from related species by its lavender blush to rosy brown pileus and fusiform cheilocystidia with sharp apices. In addition, the margin of R. dinghuensis and R. subpallidirosea is even and incurved while in R. fusiformata it is crenate. The lamellae of R. dinghuensis and R. fusiformata are rarely forked, but those of R. subpallidirosea are often forking. Moreover, the chemical reactions of cystidia and pileipellis of the three species are totally different. Pleurocystidia in R. fusiformata are SV negative, but positive in R. dinghuensis and R. subpallidirosea .

Figures

Fig. 1-2. Phylogram of subsect. Cyanoxanthinae Singer. Bootstrap values higher than 50% are shown above or below the branches. Species collected from Dinghushan Biosphere Reserve are shown in bold, the two novel species are highlighted with a blue background.

Fig. 1-3. Phylogram of sect. Ingratae Quel. Bootstrap values higher than 50% are shown above or below the branches. Species collected from Dinghushan Biosphere Reserve are shown in bold.

Fig. 6. Line drawings of basidiospores.a. Russula purpureoroseaY.Song sp. nov., holotype (GDGM75331). b. Russula fusiformata Y.Song sp. nov., holotype (GDGM 75333). Scale bar = 1 μm.

Fig. 1-1. Phylogram of Russula Pers. subgen. Heterophyllidiae Romagnesi, emend. Buyck & V.Hofst. generated using the maximum likelihood (ML) method based on rDNA ITS sequences performed by RAxML. The clades representing subsect.Cyanoxanthinae Singer and sect. Ingratae Quel. are compressed and separately displayed in Figs 1-2, 1-3. Bootstrap values higher than 50% are shown above or below the branches. Species collected from Dinghushan Biosphere Reserve are shown in bold.

Fig. 2. Russula fusiformata Y.Song sp. nov., holotype (GDGM75333). a–b. Fruiting bodies. c–d. Basidia. e. Basidiospores in Melzer’s reagent. f–g. Basidiospores under scanning electron microscope. Scale bars: a–b = 1 cm; c–e = 10 μm; f–g = 1 μm.

Fig. 3. Russula fusiformata Y.Song sp. nov., holotype (GDGM75333). a. Basidia. b. Pleurocystidia. c. Cheilocystidia. d. Pileocystidia. e. Caulocystidia. f. Pileipellis. Scale bars = 10 μm.